Decompressing¶
If you have a compressed file that is not an archive (zip or tar), you can use
pooch.Decompress to decompress it after download.
For example, large binary files can be compressed with gzip to reduce
download times but will need to be decompressed before loading, which can be
slow.
You can trade storage space for speed by keeping a decompressed copy of the
file:
from pooch import Decompress
def fetch_compressed_file():
"""
Load a large binary file that has been gzip compressed.
"""
# Pass in the processor to decompress the file on download
fname = GOODBOY.fetch("large-binary-file.npy.gz", processor=Decompress())
# The file returned is the decompressed version which can be loaded by
# numpy
data = numpy.load(fname)
return data
pooch.Decompress returns "large-binary-file.npy.gz.decomp" as the
decompressed file name by default.
You can change this behaviour by passing a file name instead:
import os
from pooch import Decompress
def fetch_compressed_file():
"""
Load a large binary file that has been gzip compressed.
"""
# Pass in the processor to decompress the file on download
fname = GOODBOY.fetch("large-binary-file.npy.gz",
processor=Decompress(name="a-different-file-name.npy"),
)
# The file returned is now named "a-different-file-name.npy"
data = numpy.load(fname)
return data
Warning
Passing in name can cause existing data to be lost!
For example, if a file already exists with the specified name it will be
overwritten with the new decompressed file content.
Use this option with caution.